+ Ok(())
+ }
+}
+
+pub struct NullOutputSink {
+ end_tx: Mutex<Option<Sender<()>>>,
+}
+
+impl NullOutputSink {
+ pub fn new() -> Self {
+ Self {
+ end_tx: Mutex::new(None),
+ }
+ }
+}
+
+impl Default for NullOutputSink {
+ fn default() -> Self {
+ Self::new()
+ }
+}
+
+impl OutputSink for NullOutputSink {
+ fn start(
+ &self,
+ event_tx: SyncSender<SoundmodemEvent>,
+ buffer: Arc<RwLock<OutputBuffer>>,
+ ) -> Result<(), SoundmodemError> {
+ let (end_tx, end_rx) = channel();
+ std::thread::spawn(move || {
+ // assuming 48 kHz for now
+ const TICK: Duration = Duration::from_millis(25);
+ const SAMPLES_PER_TICK: usize = 1200;
+ let mut next_tick = Instant::now() + TICK;
+
+ loop {
+ std::thread::sleep(next_tick.duration_since(Instant::now()));
+ next_tick += TICK;
+ if end_rx.try_recv() != Err(TryRecvError::Empty) {
+ break;
+ }
+
+ let mut buffer = buffer.write().unwrap();
+ let mut taken = 0;
+ for _ in 0..SAMPLES_PER_TICK {
+ if buffer.samples.pop_front().is_none() {
+ if !buffer.idling {
+ debug!("null output had underrun");
+ let _ = event_tx.send(SoundmodemEvent::OutputUnderrun);
+ break;
+ }
+ } else {
+ taken += 1;
+ }
+ }
+ let _ = event_tx.send(SoundmodemEvent::DidReadFromOutputBuffer {
+ len: taken,
+ timestamp: Instant::now(),
+ });
+ }
+ });
+ *self.end_tx.lock().unwrap() = Some(end_tx);
+ Ok(())
+ }
+
+ fn close(&self) -> Result<(), SoundmodemError> {
+ let _ = self.end_tx.lock().unwrap().take();
+ Ok(())
+ }
+}
+
+pub trait Ptt: Send + 'static {
+ fn ptt_on(&mut self) -> Result<(), SoundmodemError>;
+ fn ptt_off(&mut self) -> Result<(), SoundmodemError>;
+}
+
+/// There is no PTT because this TNC will never make transmissions on a real radio.
+pub struct NullPtt;
+
+impl NullPtt {
+ pub fn new() -> Self {
+ Self
+ }
+}
+
+impl Default for NullPtt {
+ fn default() -> Self {
+ Self::new()
+ }
+}
+
+impl Ptt for NullPtt {
+ fn ptt_on(&mut self) -> Result<(), SoundmodemError> {
+ Ok(())
+ }
+
+ fn ptt_off(&mut self) -> Result<(), SoundmodemError> {
+ Ok(())